Distributed Denial of Service (DDoS) Mitigation Strategy and Overview

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DDoS mitigation strategy

Bertrand Duvivier bduvivie@cisco.com BGP product manager

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DDoS Mitigation – a stepstone approach

  Phase III Dynamic application aware redirection and traffic handling

  Phase II Malicious traffic mitigation Cleaning of Malicious traffic Dirty and clean traffic handling Usage of Multi-instance BGP

  Phase I ACL RTBH PBR uRPF

IOS-XR 4.3.1 IOS-XE partial

IOS-XR 5.2.0 IOS-XE 3.1.2

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Agenda

 DDoS trends

 DDoS - Phase 2 – Architecture overview

 DDoS - Phase 3 – BGP flowspec overview

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 Distributed denial-of-service (DDoS) attacks target network infrastructures or computer services by sending overwhelming number of service requests to the server from many sources.

 Server resources are used up in serving the fake requests resulting in denial or degradation of legitimate service requests to be served

 Addressing DDoS attacks ― Detection – Detect incoming fake requests ― Mitigation o  Diversion – Send traffic to a specialized device that removes the

fake packets from the traffic stream while retaining the legitimate packets

o  Return – Send back the clean traffic to the server

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DDOS impact on customer Business

GOOD DDOS

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DDOS impact on customer Business

 Enterprise customer can’t defend themselve, when DDoS hit the FW… it’s already too late.

 SP could protect enterprise by cleaning DDoS traffic at ingress peering point.

 New revenue for SP.

 Mandated service to propose to Financial and visible customers.

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2011 DDoS trends (Nanog source)   Any Internet Operator Can Be a Target for DDoS Ideologically-motivated ‘Hacktivism’ and On-line vandalism DDoS attacks are the

most commonly identified attack motivations

  Size and Scope of Attacks Continue to Grow at an Alarming Pace

High-bandwidth DDoS attacks are the ‘new normal’ as over 40% of respondents report attacks greater than 1 Gbps and 13% report attacks greater than 10Gbps

Increased sophistication and complexity of layer-7 DDoS attacks, multi-vector DDoS attacks becoming more common

  First-Ever Reports of IPv6 DDoS Attacks 'in the Wild' on Production Networks

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DDoS mitigation architecture 1. Detection (no DDoS)

DDOS scrubber

Security Server

DDOS Analyser

Netflow

Scan Netflow data to detect DDOS attacks

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DDoS mitigation architecture 2. Detection (DDOS)

DDOS scrubber

Security Server

DDOS Analyser

Netflow

Scan Netflow data Find DDOS signature

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DDoS mitigation architecture 3. Redirect traffic to DDOS scruber

DDoS scrubber

Security Server

DDoS Analyser

Scan Netflow data Find DDoS signature

BGP DDoS Mitigation Action: redirect to DDoS scrubber

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Agenda

 DDoS trends

 DDoS - Phase 2 – Architecture overview

 DDoS - Phase 3 – BGP flowspec overview

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DDoS Mitigation: Architecture Considerations   Normal traffic flow when there is no attack

  Redirect traffic from any edge PE to any specific DDoS scrubber ― Including the PE that is connected to the host network

  Granular (prefix level/network) diversion ― Customers buy DDoS mitigation service for some prefixes ― Pre-provisioned DDoS service for those prefixes (using policy such as standard community flag)

  Centralized controller that injects the diversion route

  VPN based Labeled return path for the clean traffic ― To prevent routing loops

  Sollution support redirection of BGP less/more specific prefixes or local originated prefixes (static route, redistributed route)

  Support for multi-homed customers ― During attack, send clean traffic from DDOS scrubber to multiple PE’s

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DDoS mitigation architecture Step 1: create Clean-VPN (off attack configuration)

Security Server

DDoS Analyser

Clean VPN will transport clean traffic from scrubber back to customer next hop

DDoS scrubber

out in

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DDoS mitigation architecture Step 2: inject customers prefixes to clean Clean-VPN (off attack)

Security Server

DDoS Analyser

VRF dynamic route leaking function to inject VRF glogal prefix in VRF and VPN clean using route-map policy.

DDoS scrubber

out in

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DDoS mitigation architecture Step 3: inject BGP redirection in DDoS control plane (under attack)

Security Server

DDoS Analyser

Security server will inject BGP update with scrubber as next hop.

DDoS scrubber

out in

BGP update NH: scrubber Prefix: purple

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DDoS mitigation architecture Traffic flow under attack

Security Server

DDoS Analyser

Traffic is redirect via DDoS scrubber. Loop free solution.

DDoS scrubber

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Why injecting DDoS in separate BGP instance ?

 Sollution support redirection of BGP less/more specific prefixes or local originated prefixes (static route, redistributed route)

 Separate Inter-Domain control plane and DDoS plane No need to withdraw and re-signal Inter-Domain prefixes, keep internet route intacts in control plane.

Easy to troubleshout

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Agenda

 DDoS trends

 DDoS - Phase 2 – Architecture overview

 DDoS - Phase 3 – BGP flowspec overview

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Next-Gen BGP flowspec is RFC-5575 (aka BGP flowspec)

+ IPv6 support (draft-ietf-idr-flow-spec-v6)

+ Flowspec origin check relax (draft-djsmith-idr-flowspec-origin)

+ Extra redirection options (draft-simpson-idr-flowspec-redirect)

+ Comprehensive CLI/XML to inject BGP flowspec updates

+ Internet in VPN use-case

+ Optimized flow based forwarding plane : E-PBR (specific to ASR9K/CRS)

XR 5.2.0 XE 3.12

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Next Gen BGP flowspec infrastructure phase 1 (XML/CLI model)

BGP flowspec

BGP

BGP

XML/CLI

ACL QoS

Flow forwarding

Application

PBR

Flow Spec Manager

ASR9K/CRS

XR-VR

XML/CLI

Application VM

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Next Gen BGP flowspec infrastructure phase 2 (OnePK model)

BGP flowspec

BGP

BGP

Flow OnePK

ACL QoS

Flow forwarding

Application

PBR

Flow Spec Manager

ASR9K/CRS

XR-VR

OnePK API/SDK

Application VM

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NextGen BGP flowspec Flow encoding (phase 1)

Type 1 Destination Prefix (mask) prefix

Type 2 Source Prefix (mask) prefix

Type 3 IP Protocol udp,tcp,icmp,…

Type 4 Port

Type 5 Destination port

Type 6 Source port

Type 7 ICMP type

Type 8 ICMP code

Type 9 TCP flags

Type 10 Packet length

Type 11 DSCP

Type 12 Fragment

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Next-Gen BGP flowspec Action encoding (phase 1)

Ext Community Action Data 0x8006 traffic-rate (bw zero) BW or Drop

0x8007

traffic-action: Terminal action

(bit 7)

0x8008 Redirect (VRF) 6-byte Route Target

idr-flowspec-redirect Redirect (IP/MPLS) Next Hop

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Summary

 DDOS mitigation is a Mandatory service.

 DDOS phase 2 provides optimized architecture

 DDOS phase 3 provides flow base mitigation granularity

For more details, contact bduvivie@cisco.com

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THANKS

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DDoS phase 2

Technical details

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Architecture based on BGP multi-instance

 Two planes based on multi-instance BGP ― The default BGP instance for creating normal routing and the return path of the clean traffic ― The DDoS instance for injecting the diversion route in the routers

BGP DDos

Instance

BGP Default

Instance

DDOS RR Internet RR

PE-C

Normal routes

Diversion routes

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BGP ddos instance

router bgp 99 instance ddos bgp router-id 3.3.3.3

Creation of DDoS BGP instance

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BGP DDos

Instance

RIB

FIB

VRF default VRF Clean

BGP Default

Instance

VRF RIB

VRF FIB

BGP DDos

Instance

RIB

FIB

VRF default VRF Clean

BGP Default

Instance

VRF RIB

VRF FIB

CGSE Scrubber

C

X/Y

PE-C PE-S

VPN RR

@ RR

DDOS RR

Architecture details

  The default BGP instance uses a VRF, “Clean”, to setup the return path   On the scrubber PE, the clean traffic enters via the VRF “Clean” interface

Clean

Dirty

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BGP read-only

router bgp 99 instance ddos bgp router-id 3.3.3.3 bgp read-only

bgp read-only •  Allows config of 2th IPv4 or IPv6 instance

•  Suppresses BGP Update Generation

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BGP DDos

Instance

RIB

FIB

VRF default VRF Clean

BGP Default

Instance

VRF RIB

VRF FIB

BGP DDos

Instance

RIB

FIB

VRF default VRF Clean

BGP Default

Instance

VRF RIB

VRF FIB

CGSE Scrubber

C

X/Y

PE-C PE-S

X/Y->C

VPN RR

@ RR Route setup

 C sends X/Y to the default-VRF of the default instance of PE-C

DDoS RR

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BGP DDos

Instance

RIB

FIB

VRF default VRF Clean

BGP Default

Instance

VRF RIB

VRF FIB

BGP DDos

Instance

RIB

FIB

VRF default VRF Clean

BGP Default

Instance

VRF RIB

VRF FIB

X/Y->C

CGSE Scrubber

C

X/Y

PE-C PE-S

X/Y->C

X/Y->C X/Y->C

VPN RR

@ RR Route setup

 PE-C imports X/Y to VRF “Clean”

 PE-C downloads X/Y->C to RIB

DDoS RR

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VRF dynamic route leaking

vrf clean address-family ipv4 unicast import from default-vrf route-policy ddos advertise-as-vpn export route-target 111:1 // ddos policy = match community-string 100:123

Importing selected global route’s in the clean VRF

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X/Y->C

BGP DDos

Instance

RIB

FIB

VRF default VRF Clean

BGP Default

Instance

VRF RIB

VRF FIB

BGP DDos

Instance

RIB

FIB

VRF default VRF Clean

BGP Default

Instance

VRF RIB

VRF FIB

X/Y->C

CGSE Scrubber

C

X/Y

PE-C PE-S

X/Y->C

X/Y->C

X/Y->C

X/Y->C

X/Y->C

VPN RR

@ RR X/Y->PE-C

X/Y->PE-C Route setup

  PE-C advertises X/Y to @ RR (as IPv4) and VPN RR (as VPNv4)   PE-C RIB downloads X/Y->C to FIB

DDoS RR

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X/Y->C X/Y->PE-C

BGP DDos

Instance

RIB

FIB

VRF default VRF Clean

BGP Default

Instance

VRF RIB

VRF FIB

X/Y->PE-C

BGP DDos

Instance

RIB

FIB

VRF default VRF Clean

BGP Default

Instance

VRF RIB

VRF FIB

X/Y->C

CGSE Scrubber

C

X/Y

PE-C PE-S

X/Y->PE-C

X/Y->PE-C

X/Y->PE-C

X/Y->PE-C X/Y->PE-C

X/Y->C

X/Y->C

X/Y->C

X/Y->C

X/Y->C

VPN RR

@ RR X/Y->PE-C

X/Y->PE-C Route setup

  @ RR advertises X/Y to default VRF of PE-S and VPN RR advertises X/Y to default-VRF as a VPN route. Then the route is downloaded to RIB and FIB of default VRF and VRF “Clean”

DDoS RR

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X/Y->C

BGP DDos

Instance

RIB

FIB

VRF default VRF Clean

BGP Default

Instance

VRF RIB

VRF FIB

X/Y->PE-C

BGP DDos

Instance

RIB

FIB

VRF default VRF Clean

BGP Default

Instance

VRF RIB

VRF FIB

X/Y->C

CGSE Scrubber

C

X/Y

PE-C PE-S

X/Y->PE-C

X/Y->PE-C

X/Y->PE-C

X/Y->PE-C X/Y->PE-C

X/Y->C

X/Y->C

X/Y->C

X/Y->C

X/Y->C

VPN RR

@ RR

Attack scenario X/Y->PE-C

X/Y->PE-C

X/Y->S

  Arbor detects X/Y under DDoS attack   Arbor injects diversion route X/Y to nexthop “S” on the DDoS RR

X/Y->PE-C

DDoS RR

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X/Y->C

BGP DDos

Instance

RIB

FIB

VRF default VRF Clean

BGP Default

Instance

VRF RIB

VRF FIB

X/Y->PE-C

BGP DDos

Instance

RIB

FIB

VRF default VRF Clean

BGP Default

Instance

VRF RIB

VRF FIB

X/Y->C

CGSE Scrubber

C

X/Y

PE-C PE-S

X/Y->PE-C

X/Y->PE-C

X/Y->PE-C

X/Y->PE-C X/Y->PE-C X/Y->S

X/Y->C

X/Y->S X/Y->C

X/Y->C

X/Y->C

X/Y->C

VPN RR

@ RR

Attack scenario X/Y->PE-C

X/Y->PE-C

X/Y->S

 DDoS RR advertises X/Y->S to the DDoS instances on PE-C and PE-S

X/Y->PE-C

DDoS RR

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X/Y->C

BGP DDos

Instance

RIB

FIB

VRF default VRF Clean

BGP Default

Instance

VRF RIB

VRF FIB

X/Y->S X/Y->PE-C

BGP DDos

Instance

RIB

FIB

VRF default VRF Clean

BGP Default

Instance

VRF RIB

VRF FIB

X/Y->S X/Y->C

CGSE Scrubber

C

X/Y

PE-C PE-S

X/Y->PE-C ->S

X/Y->PE-C

X/Y->PE-C

X/Y->PE-C X/Y->PE-C X/Y->S

X/Y->C ->S

X/Y->S X/Y->C

X/Y->C

X/Y->C

X/Y->C

VPN RR

@ RR

Attack scenario X/Y->PE-C

X/Y->PE-C

X/Y->S

 DDoS instance downloads diversion route to RIB. RIB now has two paths for X/Y

X/Y->PE-C

DDoS RR

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BGP install diversion

router bgp 99 instance ddos bgp router-id 3.3.3.3

bgp read-only bgp install diversion

bgp install diversion Triggers BGP ddos instance to install

diversion path to RIB, so that the paths are pushed down to FIB

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X/Y->S

BGP DDos

Instance

RIB

FIB

VRF default VRF Clean

BGP Default

Instance

VRF RIB

VRF FIB

X/Y->S X/Y->PE-C

BGP DDos

Instance

RIB

FIB

VRF default VRF Clean

BGP Default

Instance

VRF RIB

VRF FIB

X/Y->S X/Y->C

CGSE Scrubber

C

X/Y

PE-C PE-S

X/Y->PE-C ->S

X/Y->PE-C

X/Y->PE-C

X/Y->PE-C X/Y->PE-C X/Y->S

X/Y->C ->S

X/Y->S X/Y->C

X/Y->C

X/Y->C

X/Y->C

VPN RR

@ RR

Attack scenario X/Y->PE-C

X/Y->PE-C

X/Y->S

 RIB downloads the diversion route to FIB ― Based on special flags and/or admin distance

X/Y->S

DDoS RR

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X/Y->S

BGP DDos

Instance

RIB

FIB

VRF default VRF Clean

BGP Default

Instance

VRF RIB

VRF FIB

X/Y->S X/Y->PE-C

BGP DDos

Instance

RIB

FIB

VRF default VRF Clean

BGP Default

Instance

VRF RIB

VRF FIB

X/Y->S X/Y->C

CGSE Scrubber

C

X/Y

PE-C PE-S

X/Y->PE-C ->S

X/Y->PE-C

X/Y->PE-C

X/Y->PE-C X/Y->PE-C X/Y->S

X/Y->C ->S

X/Y->S X/Y->C

X/Y->C

X/Y->C

X/Y->C

VPN RR

@ RR

  IP traffic enters PE-C (or any other PE) and finds X/Y->S in default VRF. Goes to S.

  Clean traffic from S finds X/Y->PE-C in VRF “clean” and returns to PE-C

  On PE-C, the VPN label asks the packet to do IP lookup in VRF “Clean”. Goes to C.

Attack scenario X/Y->PE-C

X/Y->PE-C

X/Y->S

X/Y->S

DDoS RR